Compact Multilayer Substrate Integrated Waveguide Dual-band Filtering Rat-race Coupler Based on Fan-shaped Cavities

摘要

A new type of multilayer dual-band filtering rat-race coupler based on fan shaped substrate integrated waveguide (SIW) cavity is first proposed in this paper. Resonant frequencies of SIW fan-shaped cavity (SIFC) have been derived to construct a resonant cell. Magnetic and electric coupling between SIFCs are realized through multiple rectangular and circular slots located on metal layer, respectively. Specifically, the multiple rectangular slots are beneficial to increase coupling bandwidth and achieve better amplitude and phase balance. Moreover, the bandwidth ratio and center frequency of two pass-bands can be flexibly controlled by adjusting the size of band-stop resonators. The detailed analysis and the design method based on coupling matrix have been introduced to realize a dual-band filtering rat-race coupler. The new type of component should be able to provide at least three functions simultaneously, including in-phase and out-of-phase power dividing, filtering, and dual-band operation. Compared with other filtering couplers, the proposed design exhibits good dual-band filtering responses, high Q factor, better isolation, amplitude balance, as well as 0 degrees and 180 degrees phase differences.